This proposal describes a study of the role of cleavage of reovirus structural proteins in regulating the onset of events in viral replication. The objective of the proposed research is to determine whether the pattern of uncoating and proteolytic activation of reovirion-associated enzymes seen in vitro also occurs in vivo. The possibility that other covalent modifications, such as protein phosphorylation, adenylation and ADP-ribosylation or RNA methylation are also involved in regulating viral functions will be examined. The long objectives of this investigation are to establish whether covalent modifications play a regulatory role in enzyme function and to gain information regarding the mechanisms regulating viral replication in eukaryotic cells.